Explaining whether, how, and why people change or stay the same over their lifetime is a fundamental issue in psychological research. This project seeks to explain changes and continuities in people's experiences of attachment security in close relationships. What happens in people's close relationships has serious implications for their welfare. Relationship problems are frequently associated with negative outcomes such as depression, violence, and divorce, to name just a few. As such, understanding why people become more or less secure in relationships over time will be important for promoting both individual and dyadic well being. The project has three goals. The first is to investigate how life experiences and the ways in which people view those experiences contribute to changes in attachment security over short and longer time periods. The second is to examine whether changes in security are more reactive to life circumstances for some people, but not others. The third objective is to examine the extent to which people experience the same levels of security across all of their romantic relationships versus base their level of security on aspects of each new relationship. These issues will be examined using diverse methods. To capture day-to-day fluctuations in security, two experiments that attempt to induce change in levels of security will be conducted. In addition, a diary study of daily experiences with a group of dating couples will be conducted to examine daily changes in security in response to real-life relationship circumstances. Finally, a longitudinal study that follows Participants over two years will be conducted to examine change and continuity in attachment security in response to important life events and new relationships. [unreadable] [unreadable]